1. Field of the Invention
The present invention relates to a semiconductor manufacturing device and, more particularly, to a device which when growing a film on a silicon substrate, accurately controls its temperature to thereby obtain a uniform film thickness.
2. Discussion of Related Art
Generally, when manufacturing a semiconductor element, film growth is accomplished by a method for growing a thermo oxide film, a chemical vapor deposition (CVD) method for forming an oxide film, and a method for forming a nitride film using an electrical furnace. The method using the electrical furnace is performed in batch-type (i.e., by the batch), which requires a significant time. As a result, any trivial mistakes occurring while processing a batch may cause defects in the wafer.
The conventional methods for manufacturing semiconductor elements require control over the temperature between the wafers in the chamber. Further, each process unit used in the conventional methods has a fixed time per process unit (time required for a process unit to perform it operation). Often, a significant time per process unit is required because the chamber temperature rises and stabilizes rather slowly. Consequently, it is difficult to reduce the turnaround time (TAT) for producing the semiconductor elements.
Therefore, a method of growing a film with a rapid thermal process unit has been introduced to overcome the above problems and to enhance productivity in accordance with integration of the semiconductor elements and the size of the silicon substrates.
As illustrated in FIG. 1, a conventional semiconductor manufacturing device includes a chamber 11, a plurality of lamps 12 disposed on the upper end of the chamber 11, wafer fixtures 13 disposed on the lower end of the chamber 11, a pyrometer 14 positioned between the wafer fixtures 13 for detecting the chamber temperature, a quartz 15 positioned between the lamps 12 and the wafer, a wafer inlet 16 formed on one side of the chamber 11, a reaction gas inlet 17 formed on the other side of the chamber 11, and a reaction gas outlet 18 formed on one side of the chamber 11.
The operation of the conventional semiconductor manufacturing device will be described below.
As illustrated in FIG. 1, the wafer is inserted into the chamber 11 through the wafer inlet 16, and then placed on the wafer fixtures 13. The lamps 12, used as a heat source, illuminate the chamber 11 and raise the chamber temperature (inside of the chamber) up to a predetermined processing temperature. The pyrometer 14 placed on the rear side of the wafer detects the chamber temperature for monitoring the temperature inside the chamber 11 for a proper film growth.
When the chamber temperature approximately reaches the predetermined processing temperature, the reaction gas is injected into the chamber 11 through the reaction gas inlet 17. For example, in case of growing an oxide film on the wafer surface, an oxygen (O.sub.2) gas is injected as the reaction gas. The oxygen gas reacts with the wafer's silicon, causing growth of an oxide film (SiO.sub.2). The predetermined processing temperature is obtained by controlling the lamps 12 using, e.g., a control circuit.
The conventional semiconductor manufacturing device as discussed previously, however, has the following problems.
First, since the chamber temperature rapidly rises up to the predetermined processing temperature, an overshoot is generated on the temperature profile, causing the temperature profile to fluctuate.
Second, it is impossible to reduce the turnaround time (TAT) because a predetermined time is required to maintain a stabilized temperature corresponding to the predetermined processing temperature.
Third, uniformity in the film is deteriorated because the film growth speed is not uniform due to unnecessary temperature elevation and temperature difference between the lamps.